Drier with circular stages and oscillating flow air inlet nozzles



Oct. 17, 1961 A. BIANCHI 3,

DRIER WITH CIRCULAR STAGES AND OSCILLATING FLOW AIR INLET NOZZLES FiledAug. 27, 1957 4 Sheets-Sheet 1 IEVENTOR. M

W Sfwh M Oct. 17, 1961 A. BIANCHI DRIER WITH CIRCULAR STAGES ANDOSCILLATING 110w AIR INLET NOZZLES 4 Sheets-Sheet 2 Filed Aug. 2'7, 1957IN V EN TOR.

WSW

6 A. BIANCHI 3,004,349

DRIER WITH CIRCULAR STAGES AND OSCILLATING FLOW AIR INLET NOZZLES FiledAug. 27, 1957 4 Sheets-Sheet 3 INVENTOR.

Oct. 17, 1961 BlANCHl 3,004,349

DRlER WITH CIRCULAR STAGES AND OSCILLATING FLOW AIR INLET NOZZLES FiledAug. 27, 1957 4 Sheets-Sheet 4 i INVENTOR. Mm 5 BY ans/MAW,

rates The present invention relates to a drier with circular stages andoscillating air inlet nozzles.

Driers are known, having circular superposed stages in which thematerial is moved by blades or other suitable means, usually fixed to acentral driving shaft.

The object of the present invention is a drier of this type possessingnovel particular characteristics which increase its efficiency.

In the known types the air is usually introduced by radial or tangentialnozzles, single or subdivided into two or three branches, or also bymeans of horizontal conduits conveying the air to several outlets spacedaround the circumference.

These systems are defective in that they create some zones moreventilated or heated than others.

This defect is the more pronounced in the case of materials which shouldnot be heated above a certain temperature and which require more time todry, or in the case of materials which during the drying process presenta critical point constituted by the passage from a given physical stateto another (for example, pasty or liquid materials which will undergohardening at a certain condition of drying).

The drier according to the invention is substantially characterized bythe fact that some, at least, of the hot drying air inlet nozzles willproduce a flow of constantly variable direction with an alternatingrepeating cycle.

The invention will now be described with reference to the accompanyingdrawings, description and drawings being given only by way of indicativeexample, non limitative of the scope of the invention.

FIG. 1 shows in a vertical axial section a preferred form of theinvention;

FIG. 2 is a partial horizontal section at one of the nozzles;

FIGS. 3 and 4 are respectively vertical sections of the materialdischarge devices at the center and at the periphery of the arrangementshown in FIG. 1;

FIG. 5 is a vertical section of a second embodiment of the drier;

FIG. 6 is a vertical section of a third embodiment of a drier accordingto the present invention.

Referring to FIGS. 1 to 4, by A is indicated the cylindrical shell ofthe drier, provided in a known way with the superposed circular stages.as drying floors 1, 2, 3 and 4 over which the material is distributedwhich during the drying operation passes from one stage to the stagenext below.

The humid material falls through the inlet nozzle 5 onto the circularchannel 6 and hence, moved by the rotating paddle 7 is discharged ontothe periphery of the first stage 1. The radial arms 8 are fastened to arotating vertical shaft 9 (driven by a motor 10') and carry paddles 1t}designed to mix up the material and drag it centerwards where it isdischarged (as will later on be described) onto the stage 2 beneathstage 1. Stage 2 is also served by rotating arms 11, while paddles 12which shove the material forwards, to the periphery, discharging it ontothe next lower stage 3.

The rotating arms 13 with paddles 14 mix up the material on stage 3 andcarry it centerwards, discharging it onto the last stage 4, whence thedried material pushed by the blades 16 fastened to the rotating arms isdischarged to the outside of the shell A through the conduit 17.

The stages 1, 2, 3 and 4 are perforated, so that dry air coming from theconduit 18 and distributed by the three conduits 19, 2t) and 21 endingrespectively beneath the stages 1, 2, and 3 may be sucked by the fan 22placed at the top of the shell A through the perforated stages and bedischarged to the outside of the shell.

The conduits 19, 2t} and 21 have a divergent shape (FIG. 2) and areradially arranged with respect to the shell. In each conduit 19, 2t) and22 a nozzle 23, 24 and 25 is disposed, each intended for distributingthe drying air. The nozzles 23, 24 and 25 are attached to a singlevertical shaft 26 which is provided at the lower end thereof with aradial arm 27 having its end pivoted to a connecting rod 28. The otherend of the connecting rod 28 is actuated by an eccentric 29 keyed on theshaft 9 driving the arms and paddles.

Rotation of the shaft 9 produces an alternating oscillation of the shaft26 and nozzles 23, 24 and 25. In other words, there is obtained acontinuous variation of the gaseous flow between the two extremedirections indicated by the arrows X and Y in FIG. 2.

That is, the flow starts from a tangential direction (or a substantiallytangential one) X which generates a circular current in the shell A inone direction; during the oscillation of the nozzle a flow is producedwhich gradually becomes radial and lastly tangential but in thedirection of Y, that is, such as to create a circular current oppositethe preceding one.

Currents are, therefore, obtained which are continually changing.

The continuous change of direction of the hot air flow in addition toensuring a good heat distribution avoids overheated zones and permits,therefore, an increase in the temperature of the incoming air, thusimproving the thermal efiiciency, productive capacity and reducing powercosts.

Obviously, the oscillating nozzle control can be realized with differentmechanical means and eventually with devices adapted to vary thetransmission ratio between the shafts 9 and 26.

Air tightness between nozzles and their conduits is realized in asufficient manner by the side fins 3t hinged at 31 to the verticalborders of the nozzles and each is guided at the free end thereof by anoscillating arm 32 fulcr'urned at 31 to the conduit and fin.

This particular construction will result in a minimum of frictionalresistances, even in the absence of lubrication, and is thereforesuitable even for a relatively high air temperature.

The efficiency of the drier according to the present invention isincreased by a special device for discharging the stages.

Materials subject to temperature limitations and slow to dry requiregreat drying surfaces, i.e. many stages, upon which the material is keptin a thin layer and quick movement.

The efficient heat distribution secured through the oscillating nozzlespermits to increase the thickness of the layers of the material to bedried and to slow down its movement, thus reducing the dimensions of thedrier. The increase of thickness is made possible with the new dischargedevices as illustrated in the FIGS. 3 and 4.

The discharge device at the center (FIG. 3) is constituted by a tubularelement 34 fixed to the stage 1, in which can axially slide a secondtubular element 35. The latter can be fixed in the desired position, forinstance by means of pressure screws 36, so as to form a kind ofadjustable height weir, over which the material must flow (arrow Z),before falling into the conduits leading towards the subjacent layer,protected in a known way by air tight valves 37. Rotating paddles of asuitable shape, in the proximity of the device 34, 35 facilitate thepassage of the material to the outlet and prevent the formation of deadpoints. 7

FIG. 4 illustrates a similar device for the peripheral discharge. Theoutlet conduit 38 is provided with an adjustable height plate 39constituting the weir and is tightly closed at the top by theoscillating vane valve 49.

The peripheral paddle l2 intended to facilitate the discharge of thematerial has the shape of a plough share or flat helicoidal sector sothat the paddle continually mixes up the lower material and carries itto the surface.

The mixing paddles lli, 12, 14, 16 may be constructed similar as paddle12.

FIGS. 5 and 6 relate to a drier similar to the drier described above,but suitable for soft or liquid but not sticky material.

Soft or liquid materials cannot generally be treated with the circularstage drier because at a certain instant they harden and stick to thepaddles and stages forming lumps and stacks.

On account of the very good heat distribution secured through theoscillating nozzles, the treatment of these materials becomes possiblewith the following devices.

The material is distributed over a horizontal circular stage in acontinuous way by at least one distributing means following asubstantially radial line; distributor and stage rotate relatively toeach other around the stage axis so as to build up a uniform layer ateach revolution, while movable pressure means press the layer down uponthe stage which is provided with holes and apertures through which thematerial descends to be treated by the gaesous drying current.

FIG. 5 shows a cylindrical shell B of the drier, and a verticalrevolving shaft 41 driven by a motor means 42 and extending along theaxis of the shell.

The material to be dried is axially introduced from above through theconduit 43 communicating with one or more radial conduits 44 providedwith downwardly directed holes or apertures through which the materialis radially discharged, falling upon the circular stage 45 solidary withthe shell B.

The conduits 44 are connected to the shaft 41 and therefore rotatetherewith so that each conduit builds up at each revolution a uniformlayer of material upon stage 45. The latter is served by'one or morepressure taper rollers 46 loosely supported by the radial arm 47, fixedto the shaft 1 and, therefore, revolving with it.

The rollers 46 can be arranged below the conduit 44, so that thematerial falls first upon the rollers and is then spread upon the stage45, or the rollers 46 can be offset relative to the conduits 44 in sucha way that the material will fall directly upon the stage 45 as a thinlayer or jet-like (according to the consistency of the material and thecharacteristics of the conduits 44) and is then compressed by therollers 46, the task of which is to laminate it and let it drip throughthe holes or apertures provided in the stage 45. The material isuniformly distributed over the stage 45 thus ensuring the bestutilization of the stage itself. The material is impinged on by the hotair entering through the nozzle 48, coming from the main conduit 49carrying the drying gas, loses a portion of its humidity and gets denserbefore falling upon the subjacent stage 50, where the taper rollers 51(similar to the rollers 46) carried by the rotating arms 52 compel it topass through the holes or apertures in the stage 50.

On the stage 50* the material may reach the critical hardening phaseonly after having remained suspended in the shape of vermicelli from thestage.

This uniform result is such as to prevent the formation of crusts andwill, of course, be conditioned by a good heat distribution due to theoscillating nozzles, as

well as to the correct dosing of the material and the quantity of heatintroduced into the various stages.

Most materials, after having been passed through two or three stagesbecome so dense as to remain broken down and they can therefore becollected on the subjacent stage 61 (after having been once moreinvested by the gaseous drying current coming from the nozzle 62)servedby the paddles 63 carried by the radial revolving arms 64. Thepaddles 63 convey the material to the finishing subjacent stages 65 and66, Where drying is completed with the normal systems of rotatingpaddles 67 and 6S transporting the material center-or peripherywards,discharging it to the subjacent stage through air tight nozzles 69 and70. The number of laminating and finishing stages depends, of course, onthe character of the material to be dried.

The stages 61, 65 and 66 are perforated in such a way that the hot airissuing from the nozzles 71, 72 and 73 may pass through the same due tothe suction from the fan 74 situated at the top of the shell B. Aportion of the aspirated air may be recycled by means of a second fan B.The laminating stages 45, 50 and 54 are only partly traversed by the aircoming from the sub-jacent stages, which passes instead throughapertures 76 and 77 of the stages alternately disposed centerandperipherywards so "as to flow over the stages themselves. The aircirculation system may also difier from the described one.

The dried material is distributed over the non-perforated bottom 78 and,pushed by the rotating paddles 79, is discharged through the chute 80.

The stages 61, 6-5 and 66 may, if necessary, have discharging devicesfor the thick layer like those already described.

In such a case also, as described for FIG. 1, the hot air inlet nozzlesare of the oscillating variety.

In the embodiment shownin FIG. 6, where the parts corresponding to thedescribed ones have been designated the same reference numerals providedwith a mark the laminating stages 45', 50 and 54 are fixed to the shaft41 and revolve with the same, whereas the distributing conduits 44', thepressure rollers 46, 51', and 55 are stationary and fixed to the shell Bby means of cross pieces 81.

It is, of course, understood that the construction details of the driermay vary from the illustrated ones without departing in any way from thespirit of the invention.

For instance, a portion of the drying stages may be of the rotating anda portion of them of the stationary type.

I claim:

1. A drier comprising, in combination, a housing having a circularperipheral wall; at least one drying floor extending transverselythrough said housing and dividing said housing into at least twochambers, said drying fioor being formed with at least one dischargeopening; a distributor means for distributing material to be dried in asubstantially even layer over said floor and for moving the materialthrough said discharge opening of said floor to the chamber locatedbeneath said floor; conduit means communicating with at least one ofsaid chambers for feeding a stream of hot gas in a directionsubstantially parallel to said floor over said layer, said conduit meanshaving an inlet end; a nozzle located at and communicating with saidinlet end and being movable in a plane substantially parallel to saidfloor from an intermediate position in which said movable nozzle isdirected toward the center of said housing to a first end position atone side of said intermediate position in which said movable nozzleextends substantially tangential to said peripheral Wall of said housingand back over said intermediate position to a second end position inwhich said movable nozzle extends on the other side of said intermediateposition also substantially tangential to said peripheral wall; moyingmeans for continuously moving said movable nozzle between said positionsthereof; and exhaust means for exhausing the hot gas from said housing,whereby the hot gas will sweep over said layer in a turbulent streamcontinuously changing its direction so that an intimate contact betweenthe hot gas and the material to be dried is obtained without overheatingthe material.

2. A drier comprising, in combination, a housing having a circularperipheral wall and a top Wall formed with a substantially centrallylocated opening therethrough; at least one drying floor extendingtransversely through said housing and dividing said housing into atleast two chambers, said drying floor being formed with at least onedischarge opening; distributor means for distributing material to bedried in a substantially even layer over said floor and for moving thematerial through said discharge opening of said floor to the chamberlocated beneath said floor; conduit means communicating with at leastone of said chambers for feeding a stream of hot gas in a directionsubstantially parallel to said floor over said layer, said conduit meanshaving an inlet end; a nozzle located at and communicating with saidinlet end and being movable in a plane substantially parallel to saidfloor from an intenmediate position in which said movable nozzle isdirected toward the center of said housing to a first end position atone side of said intermediate position in which said movable nozzleextends substantially tangential to said peripheral wall of said housingand back over said intermediate position to a second end position inwhich said movable nozzle extends on the other side of said intermediateposition also substantially tangential to said peripheral wall; movingmeans for continuously moving said movable nozzle between said positionsthereof; and exhaust means communicating with said central opening insaid top wall for exhausting the hot gas from said housing, whereby thehot gas will sweep over said layer in a turbulent stream continuouslychanging its direction so that an intimate contact between the hot gasand the material to be dried is obtained without overheating thematerial.

References Cited in the file of this patent UNITED STATES PATENTS1,136,933 Cameron Apr. 27, 1915 1,585,387 Hulse May 18, 1926 2,050,597Younger Aug. 11, 1936 2,835,050 Janetti May 20, 1958

